1. Field of the Invention
The present invention relates to an exercising device and, more particularly, to a passive exercising device.
2. Description of the Related Art
A conventional exercising device in accordance with the prior art shown in FIGS. 8 and 9 comprises a base 40, a plurality of rollers 42 rotatably mounted on and protruded outward from the base 40, a driving unit 50 mounted on the base 40 and connected with the rollers 42 to move the rollers 42 relative to the base 40, a housing 60 mounted on the base 40 to cover the driving unit 50, and a handle unit 70 mounted on the top of the housing 60 to move in concert with the housing 60. The base 40 has a surface formed with a plurality of receiving holes 41 to receive the rollers 42. The driving unit 50 includes a toothed belt 52 mounted around the rollers 42 to rotate the rollers 42, a driven gear 511 rotatably mounted in the housing 60 and meshing with the toothed belt 52 to rotate the toothed belt 52, a motor 51 mounted in the housing 60 and connected with the driven gear 511 to rotate the driven gear 511, and two idlers 43 rotatably mounted in the housing 60 and abutting an outer wall of the toothed belt 52 to stretch the toothed belt 52. Thus, the toothed belt 52 is pressed between the driven gear 511 and the two idlers 43.
In operation, the driven gear 511 is rotated by the motor 51 to rotate the toothed belt 52 which rotates the rollers 42 so as to move the base 40, the housing 60 and the handle unit 70. When in use, the rollers 42 are placed on the ground so that a user is knelt on the ground with his two hands holding the handle unit 70. Thus, the handle unit 70 is moved with the rollers 42 by operation of the motor 51 so as to perform a reciprocating motion so that the user is passively driven by the handle unit 70 to move forward and backward successively so as to exercise his arms, shoulder, chest and waist efficiently.
However, the toothed belt 52 is subjected to forces from the driven gear 511, the two idlers 43 and the rollers 42 so that the toothed belt 52 easily produces an elastic fatigue during a long-term utilization and is easily deviated or loosened from the driven gear 511 and the rollers 42, thereby affecting the movement of the exercising device. In addition, the sliding friction between the rollers 42 and the ground is not large enough so that the rollers 42 easily slip from the ground, thereby causing danger to the user during movement of the rollers 42.